Question

'M' is an element which is out of Cu, Fe, Al, Na. It shows the following properties:
(i) One of its ore is rich in M₂O₃.
(ii) M₂Os is not affected bY water.
(iii) It corrodes easily.
(iv) It forms two chlorides MCl₂ and MCl₃ identify 'M'

Answer 1

As the metal 'M' forms oxide M₂O₃ it is trivalent. Out of the metals listed, only Fe and Al are trivalent.
M₂O₃ is not affected by water, so 'M' can be out of Fe or Al.

Fe and Al both corrode easily. 

Out of Al and Fe, only Fe can form divalent chloride, so the element  'M' is Fe.